Process of carbonizing coal



March 14, 1933. T. E. w. scHUMANN 1,901,476

PROCESS OF CARBONIZING COAL Filed March 7, 1929 vnventoz THEoDoR E w.SCHUMANN Patented Mall'. 14, 1933 UNITED I STATES PATENT oFFlcE-'rnnonoa EBEEEAEDT WEENEE scnntANN, or ELIZABETH, NEW JERSEY, Ass'TGNoETo conUs'rIoN rrrILrrIEsv coEroEarIoN, or NEW Yoan, vN. Y., AcoEroEATIoN F MAINE PROCESS CARBONIZING COAL' Application led March 7,

The present invention relates to the art of .carbonizing solidcarbonaceous fuels and I, of the retort, the heat after being conducted15 "through the retort-wall first contacting w1th that portion lof thecoal adjacent lthe said walls and thereafter slowly penetrating thecharge by conduction, the rate of penetration decreasing ra idly as thedlstance between the material ing coked and the source of heatincreases. At a certain stage of this,

' Aheat treatment the highly heated coal becomes soft and pasty andforms what is known as a plastic layer, -the latter being located alonthe boundary between the green or uncoke coal at the portion of the massfarthest removed from the source, of heat and the already carbonizedcoal or coke ad'acent to the walls of the retort. This plastic-layer,consistin essentially of sem1-molten or heat-softene bituminous fuel andcertain decomposition products thereof, is practically impervious toythe assage of the ases and voltile products li er- -ated from t coalduring the coking process. Furthermore this plastic layer is anextremely poor conductor of heat, so that the flow of heat byconduction" therethrough fto the green coal from the heatedwalls o fAthe retort is vu'lidesirably slow. This seriously interferes'with andretards the carbonization process and the attendant production of coke,gas, and other products of thecoking reaction, and restricts the ca.paeity of the retort and makes necessary a .ve large vexpenditure, forapparatus of sudeient size to producecolxe and' gas in Ycommercialquantities., y

Among the principal objects of my inven- 5o tion. are:- to provide in animproved manner 192e. Serial No. 345,026.

for increasing the rate of carbonization of bituminous coal, oil shaleand ythe like in retort apparatus employing heat transmitted byconduction through the retort walls; to provide for rapidly carbonizingcoal and the like Without materially affecting in an undesirable mannereither the yields and character of tar andvother lvolatile products ofcarbonization or the appearance and character of the coke or other solidproduct of carbonization to provide for overcoming or minimizing theheat-insulating effect 'of the plastic layer? thatl normally is formeddurin the carbonizing process and which gradua ly travels inwardly fromthe heated inner wall of the carbonizing retort toward the center of thecoal charge under `present known conditions of operation; and toprovide, in a carbonizing iprocess in which such a plastic la er ofmaterial is ormedffor setting up an maintaining a predominentlexothermlc reaction (in place of the usual endolthermic reaction) inthat portion of the chargel constituting the plastic layer and inthefuel adjacent the cool side thereof.

The invention in its broadest scope is based lon the discovery that,byintroducing very limited regulated quantities of air, oxygen, or othersuitable oxygen-containing fluid into a charge' of coking coal in aretort at a point in the charge immediately adjacent to and on the coalSide of the plastic layer whe1je it is coolest, that is to say, at apoint farthest removed from the source of heat, the limited amount ofcombustion thus set up or .promoted at the coolcr surface of the plasticlayer which normally forms at the junction between the coked and theuncoked portions of the coalcharge results in the development of a smallamount of heat suf Iicient to make the reactions occurring in theplastic layen redominantly exothermic ratherfthan endot ermic, and bydeveloping additional heat at the point-where it Vis most neededgreatlyspeedsv 4up the, coking reaction. )The lair'` finds its wa -from-the cool side .tc and even graduali'y into the plastic layer, and theheat ,there generated y ,the combustion which-thereafter results has theeffect of markedly .accelerating the -35 from the external walls of theretort. In my portions of inner surface of the,

lmoyement of thsplastic layer away from the source of primary heatsupply. In a vertically disposed cylindrical retort, for example, theair is preferabl introduced into the green coal in a plura 'ty of smallstreams directed radially outward at a plurality of `points along ornear the major axisV of the cylinder throughout its length, so asto-efect an evendistribution of the air' throu h the coal. In arectangular ref tort the air would preferably be introduced at pointsnear Athe central lon 'tudinal axis 4of the retort. The air, intro ucedinto the coal in limited uantitiesm cannot pass through the plasticlayer but near the concave inner or cooler surfe; tic layer thetemperature is high enough to set up combustion between the air andsmall the various volatile by-products resulting from the decompositionof the coal. The heat thus liberated 'adjacent the said effect to theheat being. conducted toy the outer surface of this layer from theexternal heating source and materially accelerates the rate ofcarbonization and the resultant movement of the said plastic layertoward the middle or cooler portion of the charge.

.f tion set up by the small In this manner a given charge of coal in anexternally heated retort can be carbonized in afraction of the timeordinarily required in processes employed prior to my invention whereinall the heat had to be conducted to and through the charge in onedirection process theheat of the combusamount of added air is alwaysliberated where it is most effective, that is at the inner surface ofthe plastic layer uniformly over substantially the Whole ,area thereof,where the heat is utilized in carbonizing the coal and in driving olfthe volatile products simultaneously formed.

In the accompanying drawing, which shows a preferred form of apparatusfor carrying out the process, the figure is a verimproved 'tical crosssection through a coking retort showing therein a charge at anintermediate stage in the coking process.

In thedrawing, 10 is a' closed vertically,-

disposed cylindrical coking chamber or re,

tort set in a heating flue 12. The retort is provided Iwith afrusto-conical or funnel shaped base portion normally closedb a valve13. The flue 12 is rovided with a suitable hot-valve or cut-o 14 andadapted l to-receive hot combustion gases in the usual .manner from-` afurnace or the like Quot shown) through a manifold flue 16. A dischargemanifold flue 18 connects with the f upper. end of the flue 12 throughthe pipe 20 and leads to a stack, or it may lead tov a heat-recovedevice such as a waste heat boileror'the like, not shown. ,'A gas outletpipe 22 controlled by a suitable valve 24 conf ce of the plaslasticlayer adds itsnects the upplerpart of the retort 10 with a gas mamfold(not shown), from which the gases and volatile (products orcarbonization may be conducta to storage after the have been suitablyscrubbedy and purifier 7:

A hollow, heat-resistant metal pipe 26 of relatively small diameter,(for example, of one inch or less) and having one end closed, isdisposed so as to have its axis coincide with the axis of thecylindrical retort to a suitable source of supply of air or other 30oxygen-containin fluid under pressure. The said pipe may i desired beconstructedmf a heat resistant alloy such as a chromenickel-iron alloy.The cylindrical wall of the pipe 26 within the retortv 10 has its lower85" u end closed and is provided at rather closely spaced intervalsalong the middlel portion of that part of vthe ipe located within theretort with a plura 'tyof relatively small capillary apertures 28,'thearrangement pref erably being such 'that a fluid under pressure may beintroduced through the ipev into and uniformly distributed throug outthe axial portion of a' charge in said retort. The distance lowestaperture in pipe 26 may be approximately the same as that between theretort side walls and the/pipe 26.f If desired, suit\ able means may heprovided for varying from the retort bottom to the 9 the distance thatthe pipe' 26 extends into 100 the retort and for removin the said pipefrom the retort as the coklng proceeds vor when it has been completed. Avalve 30 in the line connecting 'the .pipe 26 to the source of air orthe like permits vsuitable 1 of the rate ofv air flow therethrough. Asuitable e'knclosing charging hopper 32 having the respective gas-tightinlet and outlet valves 34 and 36, is( proadjustment vided at the top ofthe retort 10 for 'use in 110 charging into the Vlatter the coal orother bituminous material to be coked. For discharging the contents ofthe retort after the `carbonization thereof is completed a. close screwlconveyor or the like 40 has one end thereof connected with the lower ordischarge end of an-air-lock or sealingy chamA ber A valve 44 in thesaid lower ends of the air-lock 42 controls the discharge of carbonizedmaterial therethrough.` The up- 1 per .end of the air-lock is connectedto the ottom of the retort 10, the passageway betgeen the two beingcontrolled by the valve When the connection with a continuousAcarbonization process, the valves 13, 44, ima fbe operatively associatedby means o a pair of lsprockets 46, 48, cooperating with a sprockl chainor the like 49. One of fthe'l y apparatus is tobe employed in sprockets46, 48K, will then be driven from ar' suitable source of power' by -anyof the well known' ower transmission devices (not shown).v he valvearrangement is such that one of the saidvalves is open when the othervalve is closed so as to effect the discharge of the contents of ther'tort without permitting access of air to the hbt material Within the.retort. The plastic layer in the case of continuous operation infanapparatus of the type shown will 'tend lto assume the general form of acone having its apex in the lower end of the'retort.

Where the process is to be carriedout intermittently, the said valve 30may if desired be equipped with anautomatic' timing device l' of wellknown type adapted for gradually cutting down and stopplng the flow ofair passing through the line 26 after the valve has been opened toinitiatethe air treatment of a charge of fuel being carbonized. `Thisarrangement gradually reduces the air flow into the retort at avpreselected rate corresponding to the reduction of' the area ineludedwithin the confines of the plastic zone as the carbonization roceeds.

In the drawin'g, 50 deslgnates an annual layer of coke lying adjacent tothe walls of the retort. A ycentral body of uncoked or green coal 52 isshown surrounding the centr'alpipe 26 in a cylindrical-shaped mass.

,'Interposed between the latter andthe annular layer of coked material lis a comparatively thin, relativel gas-impervious --annular plasticlayer 54 o coal and decomposition products thereof.

, In carrying out the process forming a part of the subject-matter ofthis invention, according to a preferred embodiment thereof inconnection with the apparatus described above, a charge of bituminouscoal or the like, either cold or-preheated to a desired degree ischarged into the retort and heat is applied to the cylindrical side walland bottom of the retort 10. After the heating has continued for asulicient length of time to cause the definite formation of a plasticlayer at or adjacent the retort walls, air,

either cold or preheated, and under a relatively small pressure, as forexample 2 lbs. per square inch, is forced radially outwardand into thecentral portion of the charge of the coal through the aperatures `in.the pipe 26g-the rate of flow of the airgbein'g preferably maintainedat a predetermined limited value, such as a rate of 2 cu. ft. of air perlb. of coal perhour, until carbonization of the charge has beencompleted. Both the charge and the central pipe 26. are 'preferably keptstationary during the process lof coking, although itis within the scopeof the invention vto-,move the said pipe through the charge or towithdraw it entirely out of the retort lduring the course of thecarbonizas tion in instances, foregample, where for any,Y

Alternatively the air pipe 26 lmay ner to maintain the relative positionof the coal particles in the said body so as to provideacontinuouscoking process utilizing the substance of the presentinvention, i. e. the introductionof regulated small amounts of air -intocontact with the plastic layer. of material formed during thecarbonization at passed slowly through t e retort in a manthe sidethereof remote from the source of.

primary coking heat, for the purpose of speeding up the coking process.In the case of a continuous carbonizing operation the -coal is fedthrough the retort at such a`rate' that all portions of theair-introducing member 26 are on the cooler side of the plastic layer,that is the side in contact with the green coal. Wh both at the sidewalls and at the bottom thereof, as shown, the gradual withdrawal upwardof the air-introducing member ensures that,as the carbonization of thecoal f progresses,lall of the air introduced into the mass will alwa sbe onthe side ofthe plastic layer remove agency.

To illustrate the effectiveness of `my improved process, the followingvaluesV lare given showing the effect of the addition of alrin themanner described upon the time required for coking a six inch layer ofcoal obtained from each of two different sources within a verticallydisposed cylindrical retort Kind of mi. Raub! air immducun. quired Nonah 2 cu. It. pel-1b. of coal per hn... Nnnn 2 cu. It. per lb. ot coal perhrmgittsburgh.

from the external' heating i ere the retort is lheated ofcarbonizationof Pittsburgh coal approx-x imately 47% and of Elkhorncoal. approximately'51%. To secure the best'results it is desirable incarrying out the process to Apreheat-the ycoal to temperaturessubstantially below 750 F.v,and preferably to temperatures within therange of from' 500- to 700 F.- out of contact with air, before thecoalis introduced into the retort and before the treatment withrair hasbeen. initiated.

By varying `within certain limits the l amounts of air witlrwhich thecoal is treated during coking the time of carbonization yis veryapprecia 1y modified. For example,y

form, rate when in amounts treatment of Pittsburgh coal in a retort ott`the type shown with 1/2 to 11/2 cu. ft. of air per 1b. of coal per hr.gives a carbonization time of 140 minutes whereas the em loyment of 1 to1% cu. ftsof air per lb. o this coal per hr. gives 'a carbonization timeof 123 minutes; and treatment of this coal with two cu. ft.- of air perlb. of coal 'per hour ,10 'Ves a carbonizationv timeof 111 minutes.

xperimental work indicates that there4 is an optimum rate of air flow oroxygen consumption which for Pittsburgh coal is approximately 2 cu. ft.of air per lb. of coal psr hr. Results obtained using apparatus o'oxygen consumption in the coking process decreases after the lastmentioned rate has Jbeen attained, and increased air flow does notthereafter markedly'decrease the time f 2 of lcarbonization although itdoes result in an increased combustion of the coke.A The oxygenpresentin the'air flowing through the coal reacts with certainconstituents opf the latter at adeiinite, approximately um-l from 1 to 2cu. ft.of air per 1b. of coal per-hr. when initially only 1/2 `cu. ft.or less of air per lb. of coal per hr. is used the oxygenapparently doesnot so react. Where air 3 in quantities of more than 2'cu. ft. per lb.

per hr. is 'employed the additionall 'of coal amount over thatspecified, while seemingly having little ei'ect upon furtheraccelerating the carbonization, apparently makes the re- 5 action hardto control and gives visible signs of coke combustion. A rate of flow ofl to 2 cu. ft. of air per pound of coal per hour may be otherwise statedas a tiow of 1/5 to 2/5 cu. ft. of free oxygen equivalent per mpound ofcoal per hour.

tial retort temperatures higher than this there is,at first an increasein the 'rate of carbonization, but this prelimlnary gain is later lostprior to completion of the coking.V

In carrying out the process with limited predetermined amounts of air, avery'small amount'of the total'charge of coal is consumed in i thecombustion resulting therefrom, the amount of coal consumed beingnormally less than 4% the type shown indicate that the rate of 'of thetotal chargethereof. The amount ofVv ,coal gas producedv morne issomewhat greater when usin air than when the same is not employe but theB. T. U. value thereof issomewhat reduced. In one instance where Chiltoncoal was carbonized in a vertical retort in a layer 6" in thickness,usinglan air flow-of 21/2 cu. ft. per

the yield of tar is somewhat less where air is employed than where noair is employed, y

the specific gravity of the tar is little affected by the described airtreatment, thoughfit may in some cases be slightly raised thereby.

vThe invention further contemplates the use in the .process 'of oxygenor of other oxygen-containing gases besides aire-or of mixturesthereof,-or of an oxygen contain'- ing gasA or gases mixed withnon-oxygen containing gases such as varlous flue gases, oxy

gen-carbon dioxide mixtures, and the like which will react with the fuelunder the conditions of carbonization and ive oii' heat. The employmentof a liquid w ich is capable of volatilizing at the temperatureprevailing in the retort so as to liberate oxygen or anoxygen-containing gas within the coal layer, such as H2O2 solution, isalso-within the scope of the resent invention.

It will be obviousito those yskilledcin the art that other designs ofcoking retorts may be employed instead of that here described and thathorizontal or inclined retorts' may be employed in place of those of thetype shown.,` Any type or shape of by-'product coke oven may be utilizedfor carrying out -los the essential features of the process when 1suitabl modified in accordance with the above isclosure.' The singlepipe described d above may be replaced by a`number of perforated pipes saced at intervals along the central plane o the retort.' In all casesthe retort is primarily heated externally and is provided with asuitable outlet for Sie escape of the volatile products formed uring thecarbonization process. It is an essential feature of this process thatsuicient heat be transmittedto the coal being carbonized,

through the exterior wall or walls ofthe retort so as to cause formationof a plastic layer or zone within the material, and sthat thereafter-'alimited controlled combustion` is set up agency and in contact with'thel relatively cooler, greenv coal. ,This limited combustion areamoves inwardly toward the center'of the green coal charge and isdirectly ahead of the plastic layer as'thelatter progresses 'in thatdirection during the carbonization.

at the face, side of the plastic layer vfarthest removed from theexternal; heating By the use of my process and apparatus as hereindisclosed, I am able to effect the varthe said fuel from an externalsource so as ious purposes of my invention and to obtain a highlysatisfactory grade of coke from bitumrinous material such as coal whilesimultaneously recovering the various valuable liquid and gaseousby-products normally formed in the coking process. The invention issusceptible of modification within the scope of the appended claims.

The invention having been thus described, what is ,claimed as new is:

1. The process of carbonizing solid bituminous fuel which comprisestransferring the major portion of the heat required for carbonizing abody of the said fuel from an external source so as to coke the fuelpro- .gressively in the direction away from thesource of heat and toform a plastic zone between the coke and lthe yet uncoked portion of thefuel, and supplying .an oxygen-containing fluid in controlled amounts tothe latter at points adjacent to the said plastic layer and only at' theside thereof farthest from the said external source of heat.

2. The process as defined in claim 1 in which air is employed vas theoxygen-containing iuid.

3. The process -as defined in claim 1 in which the oxygen-containingfluid is em ployed in amounts ranging from lSth to 2/5th cu. ft. of freeoxygen equivalent per pound of coalV pervhour of carbonizing time.

4. The process of carbonizing solid bituminous fuel comprising heating abody of fuel indirectly from an external source so as to progressivelycarbonize the fuel mass in a direction away from said source of heat andto form a plastic-layer lbetween the carbonized fuel and the yetuncarbonized fuel, and

supplying and distributing an oxygen-containing fluid to thelsaidplastic layer only on that side thereof 'adjacent the'uncarbonized fuel.

5. The process as defined in claim 4 in which the fuel to be carbonizedis preheated prior to the introduction thereinto of theoxygen-containing fluid.

6. The process of carbonizing solid bituminous fuel comprisingheating abody of the said fuel from an external source so as to progressivelycarbonize the fuel mass in a direction away from said source of heat andto form a plastic layer between the coke and the yet uncarbonizedportion of the fuel, and distributing a small amount of air to the saidplastic layer only on that side thereof adjacent the uncarbonized fuel.

7. The process of Acarbonizing solid bituminous fuel comprising heatinga body of to progressively carbonize the fuel mass in a direction awayfromsaid source of heat and to form a plastic layer between the coke andthe yet uncarbonized portion ,of the fuel, and supplying anddistributing air at rates ranging from 1 to 2 cu., ft. of air"I er poundof the fuel per hour of carbonizmg time to the said plastic layer onlyon that side thereof adjacent the uncarbonized fuel'.

8. The process of carbonizing solid'bituminous fuel which comprisesheating a body of the fuel to a carbonizing temperature by heatconducted thereto through a highly heated surrounding diaphragm,progressively carbonizing the lsaid body of fuel in a direction awayfrom the said diaphragm while maintaining a moving -plastic layer orzone between the carbonized portion ofthe .fuel and the portion thereofyet uncarbonized, the said plastic layer moving in the direction awayfrom the diaphragm, and contacting the forward surface onlyv of themoving plastic layer with a small amount of av fluid capable ofproducing an exothermcy reaction with the fuel at the said surface.

9. The process of carbonizing solid bituminous fuel, which comprisesheating a conlined body of the fuel to a carbonizing temperature inmajor part by heat conduct-ed to the .outer portion thereof through ahighlyheated sol1d diaphragm, progressively carbonizing the said body offuel in a direction away from the said diaphragm and toward the middleof the confined body so as gradually to reduce the volume of theuncarbonized remainder thereof, while maintaining a moving plastic layeror zone between the carbonized portion of the ,fuel and the portionthereof yet uncarbonized, continuously contacting the forward surface ofthe moving plastic layer with a combustion-supporting fluid and, as theheating continues, gradually reducing the amount ofcombustionsupporting'uid with whichthe fuel is contacted.

10.- The process of carbonizing solid bituminous fuel, which comprisesheating a conlfined body of the said fuel from an external sourcethrough a solid diaphragm so as progressively to carbonize the fuel inthe body 1n a direction away from` the solid diamoving plastic layer,the said air being employed in amounts ofnot more than 2 cu. ft. per lb.of fuel per hour of carbonizing time.v Intestimony whereof I aiix my siature.

THEODOR EBERHARDT WERNER SCHUMANN.

